Scleroderma and silicone breast implants.

Scleroderma, a systemic connective tissue disease, is relatively rare. Case reports of women with silicone breast implants who have developed scleroderma began appearing in the US medical literature in the 1980s. By mid-1993, of the 72 case reports of women with breast implants and connective tissue disease, 38 were reported to have scleroderma. As a result of the publication of these case reports, a number of epidemiologic studies were conducted to find out if silicone breast implants are associated with the development of scleroderma. Five case-control studies of scleroderma were done, plus four prospective studies of connective tissue diseases (including scleroderma) and breast implants. In eight other epidemiologic studies, no cases of scleroderma were identified among women with breast implants. This article includes a qualitative review of the epidemiologic studies and a quantitative summary (meta-analysis) of the case-control studies. Neither the case-control studies nor the other epidemiologic data support the hypothesis that scleroderma is associated with or causally related to breast implants.

Reproductive effects of inorganic borates on male employees: birth rate assessment.

The purpose of this study was to investigate the potential for reproductive effects of inorganic borate compounds on male employees. The standardized birth ratio (SBR) methodology was used to assess fertility among male employees, using live births as the measured end point. The ratio of female to male births was also assessed. Data were collected via questionnaires and telephone follow-up interviews. Medical insurance records were assessed for nonresponders. Exposures were assessed using three semiquantitative categories. We found a statistically significant increase in fertility as measured by live births among the employees of the inorganic borate facility. There does not appear to be any decrease in fertility due to exposures either as analyzed by the borate exposure categories or over time, which is an indirect measure of exposures. We found a nonstatistically significant increase in the percentage of female offspring. This increase was due, not to a deficiency of male offspring, but rather to a marked increase in the numbers of female offspring. This increase in percentage female offspring does not appear to be related to exposures to inorganic borates. Based on the data, exposures to inorganic borates do not appear to adversely affect fertility in this population.

Sperm shape abnormalities in carbaryl-exposed employees.

Semen was collected from 50 men occupationally exposed to carbaryl (1-naphthyl methyl carbamate) in a produciton plant for durations of 1 to 18 years and compared to semen from a control group of 34 unexposed, newly-hired workers. Employment, fertility, health, personal data, and blood samples were collected for each individual. Semen samples were analyzed for changes in sperm count, morphology, and frequency of sperm carrying double flourescent bodies (YFF). As a group, the exposed workers showed a significantly higher proportion of sperm with abnormal head shapes than did the control group (p < 0.005). Age, smoking habits, and medical problems did not appear to affect this result. This finding appears to be limited to men working in the carbaryl production area at the time of sampling. Sperm count and YFF did not show similar differences, which may be because they are known to be statistically less sensitive to small changes. Formerly exposed workers (away from carbaryl for an average of 6.3 years) showed a marginally significant elevation in sperm abnormalities compared to controls (p < .05, one-tailed statistical analyses) suggesting that the increase in abnormal morphology may not be reversible. However, the question of reversibility is sensitive to confounding factors and small sample sizes and, therefore, requires further study. With these data a definitive link between carbaryl exposure and human seminal defects cannot be established. Although a distinct effect on sperm morphology was seen in the exposed group, the increases in sperm shape abnormalities were not related to exposure dose (estimated by number of years on the job or job classification during the year prior to semen collection). Inexplicably, the increases in sperm abnormalities were seen primarily in currently exposed men who had worked with carbaryl for less than approximately 6 years. These findings suggest the need for further study since other workplace-related factor(s) may be responsible for the elevated sperm abnormalities seen in this study.

Dibromochloropropane and its effect on testicular function in man.

This study represents the largest series to date documenting the gonadotoxic effect in humans of dibromochloropropane, a widely used pesticide. Three semen analyses, serum hormonal determinations (luteinizing hormone, follicle-stimulating hormone and testosterone) as well as genital examinations were completed for 228 workers at 2 chemical production sites and consisting of a dibromochloropropane-exposed and non-exposed cohort. Parameteric and non-parametric statistical analyses of the data sets of the sperm densities from the 2 subpopulations demonstrated statistical significance (p less than 0.10) at the short-term (1.5 years) manufacturing plant. Log transformation of the sperm count and hourly exposure data were necessary to develop meaningful statistical conclusions. The serum concentration of follicle-stimulating hormone as a group mean was significantly greater at both production sites for the exposed cohort when compared to the non-exposed participants but decreased by 10 levels of magnitude when the group demonstraing shorter but more recent exposure was compared to those from the plant with longer chemical production. Finally, a dose-response model suggested significant changes in sperm density at the short-term but more recently operated production site when more than 100 adjusted hours of exposure were exceeded, while the longer operated but longer closed facility demonstrated a significant impairment only when more than 1,000 adjusted hours of dibromochloropropane exposure were surpassed. This difference in exposure data may reflect regenerative changes in the tests once the gonadotoxic substance had been removed but exact nature of the dibromochloropropane effect and the possibility of a "no effect" concentration remain to be defined clearly.

Epidemiological assessment of occupationally related, chemically induced sperm count suppression.

Occupationally related, chemically induced sperm count suppression is a recently recognized problem, first brought to light in connection with the manufacture and formulation of dibromochloropropane (DBCP). The authors studied sperm count data from four occupational cohorts - two exposed to DBCP and two exposed to epichlorohydrin (ECH). In both DBCP cohorts there was a significant difference (alpha = 0.05) between sperm count distribution functions of the exposed group and of the non-exposed group. A much higher percentage of exposed men was oligospermic and the median sperm count for each exposed group was substantially lower than that for the respective non-exposed group. In the ECH cohorts there was no significant difference between sperm count data for the exposed group and for the non-exposed group. The authors concluded that exposure to DBCP, but not to ECH, was positively associated with detectable sperm count suppression. It is suggested that the key to identifying and assessing occupationally related sperm count suppression lies in the proper classification and interpretation of group sperm count data.

Testicular function in DBCP exposed pesticide workers.

In mid-1977 a number of cases of infertility among male pesticide workers in California came to light. A description of this problem was published as a Preliminary Communication in The Lancet. A larger clinical-epidemiological study was undertaken to better understand the exposure-effect relationships involved. Of 142 non-vasectomized men providing semen samples, 107 had been exposed to 1,2-dibromo-3-chloropropane (DBCP) and 35 had not been exposed. There was a clearcut difference in both the distribution of sperm counts and the median counts between the exposed men and the not-exposed men, Of the exposed, 13.1% were azoospermic, 16.8% were severely oligospermic, and 15.8% were mildly oligospermic. Among the controls, 2.9% were azoospermic, none were severely oligospermic, and 5.7% were mildly oligospermic. Under workplace conditions, DBCP appears to have a selective effect on the seminiferous tubules.

Fatal paraquat poisoning: tissue concentrations and implications for treatment.

A 27-year-old male died 30 1/2 hours following ingestion of paraquat. Hemodialysis removed 72 mg of paraquat, which represented only 2% of the calculated absorbed dose; paraquat concentrations were determined in post-mortem tissue and were high in the lungs and kidneys. Prominent histologic changes were already present in the lungs, which showed extensive evidence of alveolar injury, and in the adrenal gland, which showed massive selective necrosis of the zonae fasciculata and reticularis. These findings emphasize the inadequacy of treatment regimens that attempt only to remove paraquat from body tissues. Trials of treatments designed to prevent gastrointestinal absorption, including combinations of absorbents, cathartics and gut lavage, are warranted.

Effect of pesticides on testicular function.

Marked impairment of spermatogenesis was found in a group of men exposed to the pesticide 1,2-dibromo-3-chloropropane (DBCP), demonstrated by semen analyses, testicular biopsies, and hormone studies. The ramifications of the use of this pesticide are discussed.

Infertility in male pesticide workers.

A number of cases of infertility were discovered among men working in a California pesticide factory. The suspected cause was exposure to the chemical 1,2-dibromo-3-chloropropane (D.B.C.P.). The major effects, seen in 14 of 25 non-vasectomised men, were azoospermia or oligospermia and raised serum-levels of follicle-stimulating hormone and luteinising hormone. No other major abnormalities were detected, and testosterone levels were normal. Although a quantitative estimation of exposure could not be obtained, the observed effects appeared to be related to duration of exposure to D.B.C.P.